The present invention relates to a semiconductor device in which a semiconductor chip and a lead frame bonded thereto via an insulating film are sealed with a resin and, more particularly, to a semiconductor device in which a semiconductor chip is mounted on the inner lead parts of a lead frame via an insulating layer.
Along with miniaturization and low profiling of semiconductor devices, lead frames with lead-on-chip (LOC) structure has been proposed. In the prior art LOC structure, a semiconductor chip is stuck on the rear surface of a lead frame using an insulating layer having an adhesive coating on both sides of an insulating film. A polyimide coating is given in the space between the semiconductor chip and the adhesive of the insulating layer. The semiconductor chip is electrically connected to the lead frame by means of bonding wires. The entire system is then sealed with a resin.
In the bonding part of the lead frame of this LOC structure, the lead frame is bonded onto the insulating layer, and the bonding part of the lead frame is electrically connected to the semiconductor chip by means of a bonding wire. In the bonding part of the prior art LOC structure as described above, the width of the inner lead is being enlarged in order to secure a wider area of bonding to the insulating layer.
In a semiconductor device employing a lead frame with the prior art LOC structure, there is a problem in that, during temperature cycling, peeling originates between the resin and the vicinity of the bonding part of the inner lead due to the difference in thermal expansion of various component members, and a crack developed with the peeling as the starting point reaches the bonding wire to break the bonding wire.